This book titled "Freshwater fishes of the Order Perciformes of Northeast India" is an attempt to update the list, nomenclatural status, systematic position and phylogeny of the perciformes fishes of northeast India. As northeast India is the region which has two biodiversity hotspots of the world: Himalayan and Indo-Burma, the region is rich in aquatic biodiversity. Upto date data of the perciformes diversity, their phylogenetic studies are of great importance from conservation point of view. Perciformes is the largest order of vertebrates and includes the most diversified group of fishes. However, inter-relationships of the fishes of the order are poorly known. Despite numerous recent papers on the morphology of the fishes of the order, it has not been possible to properly arrange the families, genera due to lack of data. Some new species have been described and revisional studies have been made in this book.